<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      // base64加密开始
      var keyStr =
        "ABCDEFGHIJKLMNOP" +
        "QRSTUVWXYZabcdef" +
        "ghijklmnopqrstuv" +
        "wxyz0123456789+/" +
        "=";

      function encode64(input) {
        var output = "";
        var chr1,
          chr2,
          chr3 = "";
        var enc1,
          enc2,
          enc3,
          enc4 = "";
        var i = 0;
        do {
          chr1 = input.charCodeAt(i++);
          chr2 = input.charCodeAt(i++);
          chr3 = input.charCodeAt(i++);
          enc1 = chr1 >> 2;
          enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
          enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
          enc4 = chr3 & 63;
          if (isNaN(chr2)) {
            enc3 = enc4 = 64;
          } else if (isNaN(chr3)) {
            enc4 = 64;
          }
          output =
            output +
            keyStr.charAt(enc1) +
            keyStr.charAt(enc2) +
            keyStr.charAt(enc3) +
            keyStr.charAt(enc4);
          chr1 = chr2 = chr3 = "";
          enc1 = enc2 = enc3 = enc4 = "";
        } while (i < input.length);

        return output;
      }
      console.log(encode64("123456."));
    </script>
  </body>
</html>
